1. Field of the Invention
The present invention relates to a method for producing a semiconductor device having a hetero semiconductor region forming a hetero junction in combination with a semiconductor base.
2. Description of the Related Art
Japanese Patent Application Laid-Open No. 2003-318398 (=JP2003318398) discloses a conventional semiconductor device. An N− type polycrystalline silicon region is so formed as to contact a first main face of a semiconductor base having an N− type silicon carbide epitaxial region formed on an N+ type silicon carbide substrate. In the conventional semiconductor device, the N− type silicon carbide epitaxial region and the N− type polycrystalline silicon region in combination form a hetero junction. Moreover, adjacent to the hetero junction between the N− type silicon carbide epitaxial region and the N− type polycrystalline silicon region, a gate electrode is formed via a gate insulating film. The N− type polycrystalline silicon region is connected to a source electrode via a source contact hole formed in an interlayer insulating film, while the N+ type silicon carbide substrate has a backface formed with a drain electrode.
In the above conventional semiconductor device, the gate electrode and the source contact hole are formed by different mask materials.